Breath of Fury, Origin of the Hidden Ones, and Concordant Crossroads

Prerequisites

• Breath of Fury on the battlefield
• Origin of the Hidden Ones on the battlefield
• Concordant Crossroads on the battlefield
• Origin of the Hidden Ones has exactly two lore counters on it
• You control at least one Assassin that does not have summoning sickness
• An opponent cannot block creatures you control

Steps

1. At the beginning of your precombat main phase, Origin of the Hidden Ones triggers, putting a lore counter on it
2. Origin of the Hidden Ones' third chapter ability triggers, causing you to create an Assassin token whenever an Assassin attacks this turn and sacrifice Origin of the Hidden Ones
3. Declare the creature with Breath of Fury attached, and at least one Assassin if the creature with Breath of Fury attached isn't an Assassin, as attackers
4. Origin of the Hidden Ones triggers, creating a 1/1 Assassin creature token that's tapped and attacking
5. Deal combat damage using the creature that has Breath of Fury attached
6. Breath of Fury triggers, causing you to sacrifice the creature it is attached to, then attach Breath of Fury to the Assassin token, then causing you to untap all creatures you control and to get an additional combat phase after this one
7. Repeat from step 3 each combat phase

Results

• Infinite LTB
• Infinite ETB
• Infinite sacrifice triggers
• Infinite death triggers
• Infinite combat phases
• Infinite untap of creatures you control
• Infinite mana creatures you control can produce
• Infinite combat damage